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In this study, the 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine content of human platelets was determined. The distribution of arachidonate among the 1,2-diacyl, 1-O-alkyl-2-acyl, and 1-O-alk-l'-enyl-2-acyl classes of choline- and ethanolamine-containing phosphoglycerides was also assessed. The major platelet phospholipids were choline-containing phosphoglycerides (38%), ethanolamine-containing phosphoglycerides (25%) and sphingomyelin (18%), with smaller amounts of phosphatidylserine (11%) and phosphatidylinositol (4%). In addition to the diacyl class, the choline-linked fraction was found to contain both 1-O-alkyl-2-acyl (10%) and 1-O-alk-l'-enyl-2-acyl (9%) species. The ethanolamine-linked fraction, on the other hand, had an elevated level of the 1-O-alk-1'-enyl-2-acyl (60%) species and a small amount of the 1-O-alkyl-2-acyl component (4%). The major fatty acyl residues found in all classes of the choline and ethanolamine phospholipids were 16:0, 18:0, 18:1 (delta 9), 18:2(n-6) and 20:4(n-6). The 1-O-alkyl and 1-O-alk-1'-enyl fraction of the ethanolamine-linked phospholipids also contained substantial amounts of 22:5(n-3) and 22:6(n-3) acyl chains. Arachidonate comprised 44% of the acyl residues in the sn-2 position of 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine. Corresponding values for the diacyl and 1-O-alk-1'-enyl-2-acyl species were 23% and 25%, respectively, based on all 20:4(n-6) being linked to the sn-2 position of all classes.(ABSTRACT TRUNCATED AT 250 WORDS)

Fast atom bombardment-tandem mass spectrometry was used to identify molecular species of paf-acether (paf) produced by human polymorphonuclear neutrophils. Using this biological material, normal phase high performance liquid chromatography was necessary prior to the fast atom bombardment-tandem mass spectrometry step. Gas liquid chromatography/electron capture detection after hydrolysis with phospholipase C and conversion to heptafluorobutyrate derivatives was used to confirm the results. The results indicated the presence of mainly 1-O-hexadecyl/octadecyl-2-acetyl-sn-glycero-3-phosphocholine, acyl analogs of paf and only trace amounts of other alkyl analogs of paf. We did not detect the 2-propionyl analog of paf. Moreover, supplementation of human polymorphonuclear neutrophils with sodium propionate did not result in formation of the 2-propionyl analog of paf.